Rotary scraping device for nodulizing drums in pelletizing plants



May 2, 1967 K. A. KALLBERG 3,316,585 ROTARY SCRAPING DEVICE FOR NODULIZING DRUMS IN PELLETIZING PLANTS Filed July 19, 1965 2 Sheets-Sheet 1 INVENTQR. K424 4/9/16 Kala-R6 BY WJWN May 2, 1 6 K. A. KALLBERG ROTARY SCRAP ING DEVICE FOR NODULIZING DRUMS IN PELLETIZING PLANTS 2 Sheets-Sheet 2 Filed July 19, 1965 m wE wq III II II III INVENTOR. KAH 1424 K4; LEA-766 BY "ix Arr/s United States Patent 3,316,585 ROTARY SCRAPING DEVICE FOR N ODULIZING DRUMS IN PELLETIZING PLANTS Karl Arne Ka'llberg, Sala, Sweden, assignor to Sala Maskinfabriks Aktiebolag, Sala, Sweden, a corporation of Sweden Filed July 19, 1965, Ser. No. 473,070 priority, application Sweden, June 16, 1965,

7,955/ 65 Claims. (Cl. 18-1) This invention relates to nodulizing or balling drums for pelletizing plants, which means drums of the type in which ore concentrate is admitted at one end of the drum and during rotation of the drum forms nodules or balls which are discharged at the other end of the drum. Within the drum the ore concentrate forms a layer which adheres to the inside of the drum and on which the nodules as well as the admitted ore concentrate are rolling. The layer of ore concentrate tends to increase in thickness and eventually to drop and it is therefore important to maintain the thickness of the layer of ore cencentrate at a suitable constant value to render possible formation of nodules in the desired manner. The object of the invention is to provide, in combination With a rotary balling drum, a suitable construction of a rotary scraping device for maintaining a constant layer of ore concentrate in the nodulizing drum.

In its broadest aspect the scraping device according to the invention is characterized in that scrapers consisting of for instance steel are mounted on an attachment extending helically on a rotary shaft which is adjustable relative to the axis of rotation of the drum. The primary purpose of the adjustability is to render possible adaptation of the distance of the scrapers from the inside of the drum and consequently control of the thickness of the layer of ore concentrate.

The attachment may be in the form of a flange extending along a steep pitch helix, for instance one turn along the full length of the shaft. The shaft may be tubular and may have mounted thereon a plurality of attachments in the form of helical flanges equally spaced apart along the circumference of the tubular shaft. In order to render possible exchange of the scrapers, they may be detachably connected to the attachment or attachments, such as by means of screw and nut joints.

An embodiment of the invention is described with reference to the annexed drawings in which FIG. 1 is an elevation of a nodulizing drum comprising a scraping device according to the invention, and FIG. 2 is a corresponding end view. FIG. 3 is an enlarged radial sectional view of the scraping device, and FIG. 4 is an axial projection of part of an attachment and a plurality of scrapers mounted thereon.

Referring to the drawing, reference numeral denotes a frame comprising a pair of pedestals 1 2, 14 which support bearings 16-, 13 for the shaft 20 of a scraping device provided in a nodulizing drum 22. The drum 22 has a pair of hooks 24 by means of which it rests on supporting rollers 26, 28. The drum is rotated by means of a motor 30 via a gear 32, the output shaft of which drives a gear wheel 34 which is in mesh with a toothed rim 36 secured to the outside of the drum. The preferably tubular shaft of the scraping device is driven at the inlet end of the drum 22 by a motor 38 via a gear 40.

The scraping device which is provided with a plu' rality of circumferentially equally spaced apart flangeshaped attachments for scrapers suitably consisting of steel is disposed eccentrically with respect to the axis of rotation of the drum 22 and can be adjusted at such a distance from the inside of the drum that a layer of ore concentrate of desired thickness can be maintained Claims 3,316,585 Patented May 2, 1967 in the drum and, consequently, an increase of the thickness of this layer beyond a certain value determined by the scraping device cannot occur. The scraping device can be adjusted due to the fact that the bearings 16, 18 of the shaft 20 are displaceably mounted on their pedestals 12, 14 for adjustment toward and away from the inside of the drum 22. As shown in FIGS. 3 and 4, the scrapers or scraping steels 44 are exchangeable due to the fact that they are connected to the respective flangeshaped attachment 42 on the tubular shaft 20 by means of screw and nut joints 45. i

The flange-shaped attachments 42 extend along steep pitch helices, for instance such that each attachment makes a single turn around the shaft 20 throughout the full length of the shaft within the drum 22. The helical shape of the flanges is more advantageous than a straight shape of axially extending flanges, because due to the helical shape, the scrapers will successively engage the layer of ore concentrate on the inside of the drum so that the forces acting on the shaft of the scraping device will be uniformly distributed.

Briefly, the mode of operation of the device is a follows. The frame 10 is preferably mounted such that the right-hand end of the drum as viewed in FIG. 1 is at a somewhat higher level than the left end. The concentrate consisting of pulverized ore in a moistened state is admitted into the drum at the right-hand open end thereof where it form a layer on the inside of the drum which layer increases in thickness according as more concentrate is fed into the drum. Due to the inclination of the drum the concentrate travels toward the other end of the drum resulting in that nodules or balls are formed from the ore concentrate which nodules are successively increasing in size as they travel toward the exit end. The scraping device prevents the layer of concentrate from increasing to a thickness such that the concentrate would drop in the form of big lumps from the inside of the drum. Instead, the scraping device maintains an adequately thick layer of concentrate. Both the shaft of the scraping device and the drum are rotating and the scraping operation is effected due to the fact that the rows of scraping steels successively engage the layer of ore concentrate and remove concentrate at the places where this layer is too thick. Due to the helical shape of the scrapers and due to the fact that a plurality of rows of scrapers are equally spaced apart around the shaft of the scraping device a very uniform layer of concentrate can be maintained on the inside of the drum. In addition, the stresses on the scraping device are moderate and uniform.

What I claim is:

l. In a pelletizing apparatus the combination of a substantially horizontai rotary drum having an inlet for ore at its one end and at its other end an outlet for nodules or balls formed from a layer of ore at the inner wall of the drum, with a scraping device, comprising a rotary shaft extending through the drum parallel to the axis of rotation thereof, a plurality of flanges extending helically along the shaft at a steep pitch helix, and scrapers mounted on said flange to have their scraping edges at a predetermined distance from the inner wall of the drum, the rotary shaft being adjustable to enable change of said distance.

2. In an apparatus as claimed in claim 1, in which the helical flanges are mounted equidistantly around the circumference of the rotary shaft, said shaft being tubular.

3. In a pelletizing drum as claimed in claim 1, and means removably mounting said scrapers on said flanges.

4. In a pelletizing apparatus the combination of a substantially horizontal rotary drum having an inlet for pulverized ore and an outlet for nodules or balls formed from a layer of ore at the inner wall of the drum with a scraping device, comprising pedestals mounted at the ends of the drum, bearings supported by said pedestals, a rotary shaft carried by the bearings in positions parallel to the axis of rotation of the shaft, parallel helical attachments mounted on the shaft and scrapers secured to said attachments, said bearings being adjustable to enable setting of the shaft to a predetermined position relative to the rotary shaft eccentrically thereto to enable adjustment of the thickness of said layer at the inner wall of the drum.

5. In a pelletizing apparatus, the combination of a substantially horizontal rotary drum having an inlet for pulverized ore and an outlet for nodules or balls formed from a layer of ore at the inner wall of the drum by a scraping device, comprising a rotary shaft of definite length, flanges mounted on the shaft and extending helically therealong through substantially one turn only for the full length of the shaft, and scrapers attached to said flanges substantially radially in relation to the rotary shaft and provided with scraper edges at their outturned ends.

References Cited by the Examiner UNITED STATES PATENTS 2,778,056 1/1957 Wynne 181 XR 2,831,210 4/1958 De Vaney 181 2,920,344 1/1960 Stirling 18-1 2,924,847 2/1960 Keiding et al. 18-1 2,947,026 8/1960 De Vaney 18-1 2,984,861 5/1961 Cox et al. 181 3,169,269 2/1965 McDowell et al 181 WILLIAM J. STEPHENSON, Primary Examiner. 

1. IN A PELLETIZING APPARATUS THE COMBINATION OF A SUBSTANTIALLY HORIZONTAL ROTARY DRUM HAVING AN INLET FOR ORE AT ITS ONE END AND AT ITS OTHER END AN OUTLET FOR NODULES OR BALLS FORMED FROM A LAYER OF ORE AT THE INNER WALL OF THE DRUM, WITH A SCRAPING DEVICE, COMPRISING A ROTARY SHAFT EXTENDING THROUGH THE DRUM PARALLEL TO THE AXIS OF ROTATION THEREOF, A PLURALITY OF FLANGES EXTENDING HELICALLY ALONG THE SHAFT AT A STEEP PITCH HELIX, AND SCRAPERS MOUNTED ON SAID FLANGE TO HAVE THEIR SCRAPING EDGES AT A PREDETERMINED DISTANCE FROM THE INNER WALL OF THE DRUM, THE ROTARY SHAFT BEING ADJUSTABLE TO ENABLE CHANGE OF SAID DISTANCE. 